Battery-powered vehicles, such as electric vehicles or hybrid electric vehicles, may contain one or more high-voltage batteries connected to a DC bus. A high-voltage battery pack may be used as the primary power source of a vehicle to drive various primary loads (e.g., traction motors) and various auxiliary loads (e.g., HVAC, lighting, pumps, etc.). During operation, the battery pack or part of it may need to be taken offline due to faulty components or conditions in the battery pack. For high-voltage battery applications, such as electric vehicles, disconnecting the battery pack may be achieved by opening a contactor connected between the battery pack and the high-voltage bus. Over time, the contactors may degrade and cause a safety hazard if they fail to open or close properly. Although a defective contactor may be detected by measuring the DC current or voltage in the high-voltage DC circuit directly, such a detection method may compromise the DC isolation between the contactor and the chassis ground to which most controller circuits are referenced. The present disclosure aims to address at least some of these considerations.